1. Field of the Invention
The present invention relates to devices for holding flexible sheets of material within a frame and particularly to a simplified frame structure which secures the material tightly across a central open area.
2. Statement of Prior Art
A previous application Ser. No. 804,062 for Interlocking Frame, filed June 6, 1977, by Norman P. O'Mullan, now abandoned, described a similar rectangular frame having an indentation along the back surface of each leg and a plurality of longitudinal strips with protrusions which engaged respective indentations to hold flexible sheets of material within the frame. The protrusion on each strip, however, was a single ridge which was relatively inflexible and did not provide sufficient locking and tightness of the material within the indentation and across the frame. Another known related prior art device is found in U.S. Pat. No. 3,594,939, issued July 27, 1971, which shows a solid rectangular picture frame having grooves around the front edges and flat longitudinal inserts which fit into the grooves over a flexible material to secure the material across the face of the frame. U.S. Pat. No. 3,757,479, issued Sept. 11, 1973, shows a flexible strip having an inverted V-shape which is pressed into an oppositely formed wide V-shaped groove around the sides of a frame to hold a flexible mirror material. A further structure is found in U.S. Pat. No. 3,987,835 issued Oct. 26, 1976, which utilizes a flexible beaded insert which engages a similarly shaped wide channel to hold a cover sheet in a rigid structure. The various other prior art structures are also either not sufficiently flexible, are difficult to assemble, or do not hold the material in a desired smooth tight secure manner across a frame.